This invention relates to a hand tool for inserting an internal retainer ring, lock ring or snap ring in a piston-pin bore and other bores.
A large portion of pistons for crankshaft engines are made to utilize an internal snap ring, referred to as a lock ring, in each end of a piston-pin bore for preventing side travel of a piston pin. Pistons for aftermarket use are supplied separately from connecting rods and piston pins for which the piston pins are used to assemble them together. Conventional assembly for repair and rebuilding of engines is a long and tedious task. It is accomplished with general-purpose tools like screwdrivers, picks and pliers with which even experienced workers often mar and damage the pistons.
There is no known hand tool for inserting the lock ring quickly, conveniently and safely in a manner taught by this invention.
Examples of most-closely related known but different devices are described in the following patent documents:
Objects of patentable novelty and utility taught by this invention are to provide a piston-pin lock-ring-insertion tool which:
decreases engine-assembly time for inserting lock rings in pistons from an hour or more to about one minute;
avoids marring of pistons with general-purpose tools now used for inserting; and decreases worker fatigue;
avoids occasional injury from use of the general-purpose tools in adverse tool-use conditions; and
can be used for insertion of a wide selection of internal retainer rings.
This invention accomplishes these and other objectives with a piston-pin lock-ring-insertion tool having a ring-insertion tube in ring-insertion relationship to a ring pusher. The ring-insertion tube has an inside periphery with a press-close taper that is tapered inwardly from a ring-feeder end to a ring-guide bore that is cylindrical uniformly intermediate the press-close taper and a ring-insertion end of the ring-insertion tube. The ring-insertion end of the ring-insertion tube has a perpendicularity surface that is adapted for alignment of the ring-guide bore and a piston-pin bore in a crankshaft-engine piston. The ring pusher has a pusher taper with a pusher head adapted for being buttressed against a side of lock ring for pushing the lock ring from a major diameter to a minor diameter of the press-close taper proximate a circumferential entrance to the ring-guide bore. The ring pusher has a slide rod that is oppositely disposed end-to-end from the pusher head. The slide rod has a cylindrical outside periphery that slides against an inside periphery of the ring-guide bore. The slide rod has an insertion plunger on a cylindrical step inwardly to a center rod that is extended concentrically from the insertion plunger.
A use method includes pushing a lock ring sidewardly with the pusher head to the ring-guide bore, reversing the ring pusher end-to-end, inserting the center rod into the lock ring, aligning the center rod with the piston-pin bore, and pushing the lock ring into an internal groove in the piston-pin bore.
The above and other objects, features and advantages of the present invention should become even more readily apparent to those skilled in the art upon a reading of the following detailed description in conjunction with the drawings wherein there is shown and described illustrative embodiments of the invention.